Open-source information repositories such as Wikipedia have changed the way knowledge is captured and disseminated, using the Internet as a perpetual worldwide editing system for a virtually unlimited digital encyclopedia. But who are the sources for the sites—and how much credence should we put in the information they provide?

Although serious questions have been raised about the reliability of the information recorded on Wikipedia, particularly by anonymous contributors, a group of researchers from Dartmouth College in Hanover, N.H., has found that anonymous and infrequent contributors to Wikipedia—whom they dub "Good Samaritans"—are as reliable a source of knowledge as those contributors who register with the site.

The concerns about the quality of information found in Wikipedia center on the nature and skills of the contributors and editors, the Dartmouth researchers say in a just-released study. Given that the creation of its content is completely open, they say, quality depends entirely on who contributes. The most reliable contributions are those that undergo the least number of changes or edits from the open-source community—and remain on the site the longest.

Because contributors have the opportunity to add, edit or delete whatever content they choose, preserving information from earlier versions is taken as tacit acceptance of its quality. Overall, the study says, registered users contribute more content than anonymous users, but anonymous users contribute higher quality content overall.

Researchers measured the retention rates of information posted by 7,058 contributors to the French- and Dutch-language versions of Wikipedia in March 2005. (The English-language version was too massive to adequately monitor.) At the time, the French site had 53,901 overall contributors, whereas the Dutch version had 33,217 contributors. The researchers also sampled an equal number of registered and anonymous contributors, although anonymous contributors outnumbered registered users by a ratio of 10 to one.

"Surprisingly, the reliability of the Good Samaritans shows that the hype around open source seems to be true, that there are benefits of people all around the world contributing to something for the larger public good," says Denise Anthony, a Dartmouth associate professor of sociology who worked on the study with Dartmouth associate computer science professor Sean Smith, and with former student Tim Williamson, who went on to become a programmer with Ning, Inc., a company that provides a free service for creating online social networks.

Researchers are not saying that all of the information on Wikipedia is completely accurate, but "this tells you that Wikipedia has the capability to be a good source of information," Anthony says.

The results were surprising, given that oversight over Wikipedia is minimal. Over the past decade, the development of open-source operating systems, databases and other programs has thrived thanks to the generous contributions of individuals who share nothing more than a common interest in the development of a particular program. Of course, these contributions are rarely anonymous and most open-source software projects have managers who have final say over what stays and what goes. Open-source information repositories do not require the same level of openness among its contributors.

Because open-source projects can increase the population that has access to a particular piece of information, "you can have thousands of people who each contribute one small thing," Anthony says. "We don't have other mechanisms that can do that. There have been social movements before that could move hundreds of thousands of people toward a certain goal, but none of them sustained the production of a good over time like this."

Open-source information repositories such as Wikipedia have changed the way knowledge is captured and disseminated, using the Internet as a perpetual worldwide editing system for a virtually unlimited digital encyclopedia. But who are the sources for the sites—and how much credence should we put in the information they provide?

Although serious questions have been raised about the reliability of the information recorded on Wikipedia, particularly by anonymous contributors, a group of researchers from Dartmouth College in Hanover, N.H., has found that anonymous and infrequent contributors to Wikipedia—whom they dub "Good Samaritans"—are as reliable a source of knowledge as those contributors who register with the site.

The concerns about the quality of information found in Wikipedia center on the nature and skills of the contributors and editors, the Dartmouth researchers say in a just-released study. Given that the creation of its content is completely open, they say, quality depends entirely on who contributes. The most reliable contributions are those that undergo the least number of changes or edits from the open-source community—and remain on the site the longest.

Because contributors have the opportunity to add, edit or delete whatever content they choose, preserving information from earlier versions is taken as tacit acceptance of its quality. Overall, the study says, registered users contribute more content than anonymous users, but anonymous users contribute higher quality content overall.

Researchers measured the retention rates of information posted by 7,058 contributors to the French- and Dutch-language versions of Wikipedia in March 2005. (The English-language version was too massive to adequately monitor.) At the time, the French site had 53,901 overall contributors, whereas the Dutch version had 33,217 contributors. The researchers also sampled an equal number of registered and anonymous contributors, although anonymous contributors outnumbered registered users by a ratio of 10 to one.

"Surprisingly, the reliability of the Good Samaritans shows that the hype around open source seems to be true, that there are benefits of people all around the world contributing to something for the larger public good," says Denise Anthony, a Dartmouth associate professor of sociology who worked on the study with Dartmouth associate computer science professor Sean Smith, and with former student Tim Williamson, who went on to become a programmer with Ning, Inc., a company that provides a free service for creating online social networks.

Researchers are not saying that all of the information on Wikipedia is completely accurate, but "this tells you that Wikipedia has the capability to be a good source of information," Anthony says.

The results were surprising, given that oversight over Wikipedia is minimal. Over the past decade, the development of open-source operating systems, databases and other programs has thrived thanks to the generous contributions of individuals who share nothing more than a common interest in the development of a particular program. Of course, these contributions are rarely anonymous and most open-source software projects have managers who have final say over what stays and what goes. Open-source information repositories do not require the same level of openness among its contributors.

Because open-source projects can increase the population that has access to a particular piece of information, "you can have thousands of people who each contribute one small thing," Anthony says. "We don't have other mechanisms that can do that. There have been social movements before that could move hundreds of thousands of people toward a certain goal, but none of them sustained the production of a good over time like this."

Anthony is now considering a study that would compare the IP addresses of anonymous contributors with information provided by registered Wikipedia contributors. "That might tell us,'' she says, "who the Good Samaritans are and why they do what they do."

Anthony is now considering a study that would compare the IP addresses of anonymous contributors with information provided by registered Wikipedia contributors. "That might tell us,'' she says, "who the Good Samaritans are and why they do what they do."

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